In Nature of Idiotypes Associated with Anti-p-azophenylarsonate Antibodies in A/J Mice

Antiphenylarsonate (anti-Ar) hybridomas were prepared according to Milstein and Köhler with the cell line 45.6TG1.7 and A/J spleen. About 20% of initial wells with anti-Ar activity expressed the major A/J cross-reactive idiotype. Many wells contained anti-Ar antibodies whose binding to Ar-coated plates was strongly inhibited by antiidiotypic (anti-id) antibody but which did not compete effectively with labelled serum antibody for anti-id. Three such hybridoma products (HP) were cloned twice in agar; a 4th was cloned once. All were IgG1K. Each of the four HP, when specifically purified from a BGG-Ar-Sepharose and then radiolabelled, was strongly bound by anti-id. Pooled purified anti-Ar antibodies and anti-Ar antiserum from 9 of 10 mice competed with each HP for anti-id. The serum of the mouse which was non-inhibitory contained normal amounts of the major cross-reactive idiotype. These results demonstrate the presence of cross-reactive anti-Ar idiotypes other than the major idiotype in the A/J strain. Such idiotypes represent a small proportion of the anti-Ar population. Serological analysis of the four HP, which may reflect the serum antibody population, suggest that these "minor" idiotypes may be quite heterogeneous. An HP which did compete with the major cross-reactive idiotype for anti-id failed to compete with three of the four HP described above. This provides support for the concept that the "minor" idiotypes are serologically distinct from the major cross-reactive idiotype.